# std::chrono::gps_clock

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< cpp‎ | chrono

Defined in header `<chrono>` |  |
class gps_clock; |  | (since C++20)

The clock `std::chrono::gps_clock` is a Clock that represents Global Positioning System (GPS) time. It measures time since 00:00:00, 6 January 1980 UTC.

Leap seconds are not inserted into GPS. Thus, every time a leap second is inserted into UTC, UTC falls another second behind GPS. As of December 2017, UTC is 18 seconds behind GPS, reflecting the 18 leap seconds inserted between 1980 and 2017. Thus, 2018-01-01 00:00:00 UTC is equivalent to 2018-01-01 00:00:18 GPS. GPS is a constant 19 seconds behind TAI.

`gps_clock` meets the Clock requirements. It does not meet the TrivialClock requirements unless the implementation can guarantee that `now()` does not throw an exception.

### Time point family

Defined in namespace `std::chrono` |  |
template<class Duration> using gps_time = std::chrono::time_point<std::chrono::gps_clock, Duration>; |  | (since C++20)
using gps_seconds = gps_time<std::chrono::seconds>; |  | (since C++20)

operator<<(std::chrono::gps_time) (C++20) | performs stream output on a `gps_time` (function template)
from_stream(std::chrono::gps_time) (C++20) | parses a `gps_time` from a stream according to the provided format (function template)
std::formatter<std::chrono::gps_time> (C++20) | formatting support for `gps_time` (class template specialization)

### Member types

Member type | Definition
`rep` | signed arithmetic type representing the number of ticks in the clock's duration
`period` | a std::ratio type representing the tick period of the clock, in seconds
`duration` | std::chrono::duration<rep, period>, capable of representing negative durations
`time_point` | std::chrono::time_point<std::chrono::gps_clock>

### Member constants

constexpr bool is_steady [static] | true if the time between ticks is always constant, i.e. calls to `now()` return values that increase monotonically even in case of some external clock adjustment, otherwise false (public static member constant)

### Member functions

now [static] | returns a std::chrono::time_point representing the current point in time (public static member function)
to_utc [static] | converts a `gps_time` to `utc_time` (public static member function)
from_utc [static] | converts a `utc_time` to `gps_time` (public static member function)

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